Process for oxidizing gasseous hydrocarbons



Allg 22, 1933- .11. E. BLUDWORTH PROCESS FOR OXIDIZING GASEOUSHYDROCARBONS Filed Dec. 24, 1930 A N ENS All kuwzu Patented Aug. 22, l1933 UNITED )STATES PROCESS- FOR OXIDIZING GASEOUS HYDBOCABBONS JosephE. Bludwmh, Eastland. Tex., einer to Hanlon-Buchanan, Inc., Tulsa.,Okla.

Application December 24, 1930 Serial No. 504,636

p '4cm (cuco-15s) This invention consists in new and useful improvementsin a process of oxidizing gaseous hydrocarbons to produce a mixturecontaining methanol, acetone, a'cetaldeh'yde, and similar chemicals andconstitutes an improvement on the process described and claimed in mycopending application led of even date herewith.

My present invention is particularly directed to a means for moreaccurately controlling the rate and degree of reaction, thereby makingit possible to appreciably increase the percentage of methanol, acetone,acetaldehyde and other chemicals formed by the reaction of oxygen uponthe hydrocarbons, and more completely eliminating the formation ofundesired materials such as acids, carbon and formaldehyde. It isobvious that water is always formed as a by-product cf the oxygenreaction in processes of this character.

As stated in my co-pending application. it is a well-known law ofphysical chemistry thatl action, by causing a plurality of injections ofair or other oxidizing gas at successive points in the reaction zone, ascontrasted` with the total introduction of air or other oxidizing gas atthe outset of the process as called for in my copending application.

With the above and other objects in View which will appear as thedescription proceeds, my invention consists in the novel features t5`herein set forth,- illustrated in the accompanying drawing, and moreparticularly pointed out in the appended claims. l.,

' Referring to the accompanying drawing, in which numerals of likecharacter designate similar -parts throughout both views,

Fig. 1 is a schematic layout of one form of apparatus by which my`process may be pracy tied,`and

Fig. 2 is a modification showing.- one form of heating element orreaction zone for facilitating the multiple injection of oxidizinggas'according to my invention. In the drawing, referring to Fig. 1, 1represents a pipe line for conducting the gaseous hydrocarbon, such forexample as propane or butane or mixtures of the same into the system,and is provided with a. meter 2 and a manometer 3 for indicating thevolume and pressure respectively of the hydrocarbon entering thesystem.The line 1 terminates at the inlet of a compressor 65 4, the dischargeside of which is connected to a pipe line 5 which leads to the interiorof a mixing chamber 6, which is in communication with the coils 7 in thefurnace 8 through the medium of the pipe line 9.

10 represents an air or oxidizing gas line which leads from any suitablesource to a second compressor 11, the discharge outlet of which isconnected toY a pipe line 12, the latter leadingto therethrough. As inthe case of the pipe line 1f,

the pipe line 10 is equipped with a suitable meter 16 and manometer. 17at points anterior to the compressor 11. K

The pipe line 13 is connected as at 18 to the pipe line 5 which leads tothe mixing chamber 6, for injecting an initial quantity of oxidizinggasinto the mixing chamber. 'Ihe pipe line 14 85 leads to a point in theheating or reaction coil` 7 designated by the numeral 19, said point inthe reaction zone being determined by the temperature at that particularpoint. The pipe line l15 90 leads to a second point 20 in the reactioncoil 7, which point as in the case of -the connection at 19, isdetermined by temperature and in addition, the time of passage throughthe reaction zone. 95

It will be understood that while I have shown one initial injection ofoxidizing gas and two additional injections in the reaction zone, I mayemploy a lesser or greater number of injections, according to thecharacter of the apparatus used 10b and the end products desired.

21 represents a suitable cooler or condenser into which the mixture ofhydrocarbonV and oxidizing gas passes through line 22, after leavingthereaction coil 7, discharging from the condenser through line 23 into aseparator 24, the lower extremity of said separator forming a A. liquidaccumulator which terminates in a liquid draw-oir 25. The upper end ofthe separator 24, as in my co-pending application, may be provided witha series of bales 26, and opens 110 therein, a. gas reservoir 31, whichserves as a source of supply tor the compressor ,30.

The compressor 30 is connected with the interior of the mixing chamber 6through' the medium of a pipe line 32, whereby the com'- pressed vaporsare circulated through the system as will be hereinafter set forth.

Referring to Fig. 2 of the drawing, the furnace 8 is of the indirectheating type, being provided with a masonry baille wall 8abetween theburner and the series of coils -7. With this structure, the mixture ofhydrocarbon and the initial charge of oxidizing gas enters at 9a, theadditional injections of oxidizing gas, as with the apparatusheretoforedescribed, being made at the points 19 and 20.

Having thus described the layout of one form oi apparatus bywhich myprocess may be practiced, its operation is as followsz- Y A saturatedgaseous hydrocarbon is introduced into the system through the pipe line1, the charge being compressed by the compressor 4 and passing throughline 5 into the mixing chamber 6.I Simultaneously, air or otheroxidizing gas from line 10 is compressed by the compressor 11 anddischarged into line 12, from whence, through the medium of line 13, itis injected in the line 5 at the point 18, thus entering the mixingchamber 6 along with the charge of gaseous hydrocarbon. It will beunderstood that all gas volumes are corrected to standard conditions oftemperature and pressure before entering the apparatus. The compressors4 and 11 compress the hydrocarbon gasand oxidizing gas respectivelyunder'the desired pressure, preferably above 200 pounds per square inch.

The mixture entering the mixing chamber 6 is then mixed with a quantityof recycled gas from line 32 as will b e hereinafter referred to, andfrom thence conductedl to the reaction coil I in thefurnace 8, thetemperature of which is preferably maintained between 450 and 900 F.

During the passage of the mixture through the reaction zone, additionaloxidizing gas is injected at points 19 and 20 and it will be understoodthat the quantity of oxidizing gas introduced into the mixture at anyone point in the apparatus is only sufficient to cause a series' ofsuccessive controlled reactions. In other words, a suflicient quantityof oxidizing gas is introducedat 18 to cause an oxidizing reaction uponthose compounds which oxidize at temperatures below 400 F., forexample,rwhich is partially the result of the heat of compression fromthe compressors 4 and 11. Byrthev time the mixture has reached the point19 in the reaction zone, the oxygen content thereof has been completely.utilized by the hydrocarbon, and the saturated hydrocarbons, due to theelements of temperature, time and pressure, are in a state to be actedupon by additional oxidizing gas when it is injected at the point 19.

During the passage of the mixture of gaseous hydrocarbon and newlyinjected oxidizing gas from the point 19 to the point 20 in the reactionzone, further reactiontakes place due to the elements of time andtemperature. While the temperature between these two points is notmaterially raised above that of the point of the injection at 19, thetime of passage between these points is largelyk responsible for thecomplete utilization of the charge of oxidizing gas introduced at 19,and those compounds which oxidize at temperatures below 900 F.,'forexample, are caused to undergo an oxidizing reaction.

After the point 20 in the reaction zone, there may remain in the mixturea number of saturated hydrocarbons-which are in a state to be furtheracted upon by additional oxidizing gas, and the injection of suchadditional oxidizing gas at the point 20 causes a further reaction uponthose hydrocarbons, due to the element of time of passage through theremainder ofv the reaction zone.

From the reaction zone, as in the case of my co-pending application, themixture is conducted through pipe 22 to the condenser 21 where a portionof the mixture is condensed, both the condensed and uncondensed'portions being then transferred to the separator 24 where the condensateaccumulates in the lowerend, said condensate forming the desired mixturewhich includes methanol, acetone, acetaldehyde and other chemicals asbefore stated, which chemicals may be removed or separated from themixture by fractionating or-other known means, which form no part ofthis invention.

At the upper extremity of the separator 24, the uncondensed vapors areseparated into two streams, one leading through pipe 27 to vent, themajor portion of the uncondensed vapors being led through pipe 28 to thereservoir 31, which serves as a source of supply for the compressor 30.The vgas from the reservoir 31 is compressed by the compressor 30 andreturned to the system by means of the pipeline 32 and the mixingchamber 6 where it is completely mixed with the charge of freshhydrocarbon gas vand oxidizing gas introduced through pipe 5.

The mixture of fresh hydrocarbon gas, oxidizing gas, and recycled gas isthen led through the reaction zone and condenser repeating the cyclejust described.

As stated in my co-pending application, valved connections are placed onthe various parts of theequipment in order to control pressures andrates of flow, and the pressures are indicated by suitable gauges placedon different parts of the equipment. I have found that the operation canbe carried out under a considerable range of pressures, but fromexperience have determined that they should preferably be as beforestated, in excess of v200 pounds per squareinch in the reaction zone. Ihave likewise found that the process can be carried out under aconsiderable range of temperatures, but in practice have found that thisshould preferably be in excess of 450 F. in the reaction zone. Ontheother hand, I have found that temperatures higher than 900 F. areundesira-` ble and do not permit of the definitely controlled vcharacter of reactionv which constitutes one of lustration, when anultimate yield of eight gallons of. desired liquid products (methanol,acetone, acetaldehyde) are to,be produced from one thousand cubic feetof butane, I would produce not in excess of five ten thousandths(0.0005) gallons per pass based on each cubic foot of raw butane used,and usually only about two or three ten thousandths (0.0002) gallon. Tobring about this controlled quantity of reaction, I introduce onlysufcient air or oxygen to permit ofsuch a degree of reaction. Thespecific character of my invention can probably be better understoodwhen I state that at no time in the reaction zone do I permit the oxygencontent to materially exceed 1.25% of the mix in the reaction zone orfall below .4%. For example, when using propane as raw material, I foundthe composition of the material enter- By recycling the reactinghydrocarbon a sufficient number of times to complete the reaction of allof the hydrocarbons for example fifteen (15) or more times and on eachrecycle introducing only a small amount of air, the reaction iscontrolled so that over-oxidation is not affected, which means that Ican produce methanol, acetone and acetaldehyde Without the formation ofquantities of undesirable products such as acids, carbon, etc. By myprocess, methanol, acetone and acetaldehyde are formed simultaneously or-rather are taken from the process simultaneously but I have found thatwhen the reaction is permitted to go to say .0005 gallons of methanol,acetone and acetaldehyde per pass, then a greater percentage ofacetaldehyde is formed than when such reaction is permitted to-go toonly .0003 gallons per pass, based on each cubic foot of raw butaneused. By decreasing the quantity of reaction per pass I can verymaterially decrease the percentage of acetaldehyde formed andcorrespondingly increase the methanol. In other words, there is aconsiderable flexibility in the relative percentage of methanol andacetone on the one hand and acetaldehyde on the other, depending on thepercentage of reaction permitted per pass. On the other hand, when thepercentage of reaction perpass is permitted to materially exceed .0005gallons per pass, then the beneficial results of my process no longerare available because the reaction promptly gets out of control. Inpractice, I find that a desirable ratio of recycle mix to fresh mix tobe about 96% recycle and about 4% fresh butane or propane, in which casethe reacting agent would pass through the reaction zone more thantwenty-four times.

In using butane as raw material this 4% fresh butane would be mixed withthree to ve parts (by volume) of air and one part of butane, which inturn would mean that the material entering the reaction zone would be.three or five parts air to about twenty-five parts of material otherthan air, i.e., recycle and fresh hydrocarbon. The preferred rawhydrocarbons for .my process are propane and butane, although I havefound yit useful when using other hydrocarbons.

Starting with butane, I have recovered as high as eight gallons ofmethanol, acetone and acetaldehyde, of which six gallons was methanolwith one gallon each of acetone and acetaldehyde. These results Wereobtained when the reacting material was passed through the reaction zoneabout thirty (30) times and on each pass exposed to reactiontemperatures for not more than 30 seconds.

Using commercial propane as raw material I have produced up to sixgallons of methanol, acetone, acetaldehyde from 1000 cubic feet of rawmaterial, with the relative percentage of the three desired end productssubstantially the same as when using butane as raw material. Aspreviously stated the relative percentage of acetaldehyde can beincreased by permitting a greater percentageof reaction per pass withfewer total passes. For example with from fifteen to twenty passes (15to 20) l there-was formed about two gallons of acetaldehyde from 1000cubic feet of rawbutane. l

In the run where I formed the eight gallons of methanol, acetone,acetaldehyde liquid, exclusive of the Iwater by-product which always isformed, I used a temperature in the reaction zone of about 700 F. and apressure of about 300 pounds. The quantity of residual gas dischargedfrom the system through pipe 20 obvously is a function of the number ofpasses and the quantity of fresh hydrocarbon-air mix introduced into thesystem, as Well as the operating pressure. The quantity of this-residualgas released can be' automatically controlled byl means of a pressurerelease valve which is set at any desired operating pressure. It Will benoted that the B. t. u. content and quantity ofthis` residual gas can bevaried at will.

The essence of the present invention lies' in,

the multiple introduction of oxygen or air into successive parts of thereaction zone, as contrasted with the total introduction at one place inmy co-pending application. It is possible that by injecting the fullproportion of air at one point of the process might under certainconditions so heavily impregnate the gas mixture with oxygen that thereaction would proceed to a point that would be detrimental to thequantity and quality of the lproducts produced, because of appreciablepercentages of unsaturated hydrocarbon materials which unsaturatedmaterials are particularly sensitive toward reaction with oxygen yunderelevated temperatures prevailing.

This condition can be largely controlled accord- 1 ing to my presentinvention; by introducing the iii forth in the following claims.

oxygen or air at successive points or stages in the heating coil orreaction zone. By way of" example, I have found that the reaction canvery definitely be controlled by introducing one-half of the totalweight of oxygen used prior to-the initial point of inlet to thereaction zone making this entry in company with the'recycle material andthe new or fresh butane or propane; onefourth of the oxygen or air to beintroduced at a point one-third of the length of the heating coil orreaction zone; and the remaining one-fourth, two-thirds the length ofthe heating coil or reaction zone. Actual increase of production ofmethano1,acetone and acetaldehyde from propane or butane of fromlO to20% have been achieved. During this multiple stage introduction of air Ihave observed the following temperature conditions in the reaction zoneor coil. At the initial point of entry the temperature was about 350 F.,at the second point of air injection the temperature was 750 F., and atthe third point of air injection the temperature was 750 F., while atthe exit of the coil or reaction zone the temperature was about 700 F.From these temperatures observed it is to be noted that the temperaturethroughout the reaction zone does not exceed a desired temperature, inthis case 750 F., whereas if total injection of air or oxygen were madeat the initial inlet the temperature attained during the first part ofthe reaction zone might not be controlled and excessive oxidation mightoccur in the formation of undesired carbon monoxide, carbon dioxide,formaldehyde and acids. If total injection of the oxygen is made at theinlet of the reaction coil as in my co-pending application I have foundthe composition of the incoming material using propane as raw materialto be about as follows: 67.5% nitrogen, 0.9% oxygen, 5% CO, 6% CO2, 1.8%ethylene, 2.8% of hydrogen and 16% propane. From experience I havedetermined that this 0.9% oxygen, while apparently very small, is stilltoo high to best control the reaction. By introducing only half of theoxygen at this inlet the above percentage of 0.9% would obviously bereduced to 0.45%, with which percentage I find that I can far bettercontrol the oxidation to bring about the desired end product and reduceto a minimum the undesired end products. In broad terms the object of myinvention is to maintain substantially uniform throughout most of thereaction zone, the percentage of available free oxygen, and at all timessaidpercentage being between 0.4 and 1.25 per cent.

It will be noted that, as in the case of my copending application, mypresent invention does not contemplate the use of catalysts in any form.

From the foregoing it is believed that the objects, advantages, andoperation of my improved,

process may be readily understood by those skilled in the art withoutfurther description, it being borne in mind that numerous changes may bemade in the details of structure of the apparatus as well as theprocess, Without departing from the spirit of my invention as set Forexample, while I have mentioned the use of butane and propane as rawmaterials, it is to be understood that these are merely illustrative,and I may use other raw materials, preferably however, those consistingmainly of a saturated normally gaseous hydrocarbon or mixtures ofvarious saturated gaseous hydrocarbons.

Ahyde which comprises mixing a saturated hydro- What I claim and desireto secure by Letters Patent is:

1. A process for the manufacture of a mixture containing methanol,acetone and acetaldehyde which comprises combining a saturatedhydrocarbon gas with a suitable oxidizing gas having the oxidizingcharacteristics of air, compressing said mixture and passing the samethrough an elongated passageway of restricted cross section, heating themixture as y,it flows through the passageway to between 450 and 900 F.to cause partial oxidation of the hydrocarbon gas, introducing into themixture as it ilows through said passageway and before it has beenheated to the maximum degree, an oxidizing gas having the oxidizingcharacteristics of air, then cooling the mixture to effect conden-`sation of a portion thereof, collecting the condensate, and cyclingcontinuously a portion of the uncondensed gases and vapors for admixturewith the combined fresh saturated hydrocarbon gas and an oxidizing gas.

2. A process for the manufacture of a mixture containing methanol,acetoneand acetaldecarbon gas with an oxidizing gas having the oxidizingcharacteristics of air, compressing said mixture and then heating thesame to a temperature of about 400 F. to cause an oxidizing reactionupon those compounds which oxidize at` temperatures below 400 F., thenraising the temperature of the mixture to between 450 F. and 900 F.,injecting a quantity of oxidizing gas having the oxidizingcharacteristics of air into the mixture at a point during said increasedheat step to cause an oxidizing reaction upon those compounds whichoxidize at temperatures between 450 F. and 900 F., then 'I cooling themixture to effect condensation of a portion thereof, and collecting thecondensate.

3. A process for the manufacture of a mixture containing methanol,acetone and acetaldehyde which comprises mixing a saturated hydrocarbongas with an oxidizing gasA having the i oxidizing characteristics ofair, compressing said mixture and then heating the same to a temperatureof about 400 F. to cause an oxidizingv reaction upon those compoundswhich oxidize at temperatures below 400 F., then rais- 125 ing thetemperature of the mixture to between 450 F. and 900 injecting aquantity of oxidizing gas having thek oxidizing characteristics of airinto the mixture at a point during said increased heat step to cause anoxidizing reaction upon those compounds which oxidize at temperaturesbetween 450 F. and 900 F., then injecting into the mixture at a secondpoint during the increased heating step, an additional amount of anoxidizing gas having the oxidizing characteristics of air, to causeV anoxidizing reaction upon those compounds which oxidize at a temperaturebetween 450 F., and 900 F. but o'ver a longer reaction period,

then cooling the mixture to effect condensation of a portion thereof,and collecting the condensate. f

4. A process for the manufacture of a mixture containing methanol,acetone and acetaldehyde which comprises mixing a saturated hydrocarbongas V,with an oxidizing gas having the oxidizing characteristics of air,compressing said mixture and then heating the same to' a temperature ofabout 400 F. to cause an oxidizing reaction upon those compounds whichoxidize at temperatures below 400 F., then rais- :150

reaction upon those compounds which oxidize at a temperature between 450F. and 900 F. but over a longer reaction period, then cooling themixture to effect condensation of a portion thereof, collecting thecondensate, and cycling continuously a portion of the uncondensed gasesand vapors for admixture with the combined fresh saturated hydrocarbongas and an oxidizing gas.

JOSEPH E. BLUDWORTH.

